Continuous casting apparatus having bent-edge belts



Sept. 5, 1967 E. o. SCHERRER CONTINUOUS CASTING APPARATUS HAVING BENT-EDGE BELTS 2 Sheets$heet x Filed Jan. 28, 1965 INVENTOR. ELMER D. SCHERQER,

ATTORNEYS.

Sept. 5, 1967 E. D. SCHERRER 39,6 5

CONTINUOUS CASTING APPARATUS HAVING BENT-EDGE BELTS Filed Jan. 28, 1965 2 Sheets-Sheet 2 INVENTOR. ELMEQ D. SCHERREE,

ATTORNEYS.

United States Patent Ohio Filed Jan. 28, 1965, Ser. No. 428,664 12 Claims. (Cl. 164-278) ABSTRACT OF THE DISCLOSURE Continuous casting apparatus for molten metal having upper and lower traveling casting belts with coacting flights mounted one above the other for longitudinal movement in the same direction, the coacting flights defining a casting cavity therebetween for the introduction of molten metal, the casting belts being formed from spring steel and having their opposite marginal side edge bent outwardly away from each along permanently set lines of bend with the lines of bend in the upper and lower belts in vertical alignment so that when the coacting flight-s are contacted by rollers which place the belts under lateral restraint, the portions of the belts adjacent the lines of bend will be reversely bent to define a generally rectangular cavity the opposite sides of which are closed by the reversely bent portions of the belts,

This invention relates to apparatus for casting metal strips directly from molten metal, and more particularly to apparatus for continuously casting metal strips between a pair of continuously moving casting surfaces which confine the molten metal therebetween and carry the molten metal along as it solidifies into a strip while maintained between the casting surfaces.

In such apparatus the casting surfaces usually comprise a pair of endless metal belts which are brought into spaced relation to form a casting cavity therebetween into which the molten metal is deposited, the metal being introduced into the cavity through an elongated spout projecting inwardly between the belts from the leading end of the apparatus. The belts may be either planar throughout their travel, or they may be initially bowed in cross-section by shaping rolls which initially form the belts into a general elliptical shaped cavity. As the bowed belts are advanced their bowed configuration is reduced and the belts brought into generally parallel spaced relationship to define the thickness of the finished product. Such spaced relationship is maintained until the metal has solidified sufiiciently to retain its integrity as a strip, whereupon it is discharged from the exit end of the apparatus. In addition to determining the shape of the strip being formed, the metal belts serve as chilling surfaces which assist in the solidification of the molten metal, the exterior surfaces of the belts being in contact with a continuously circulating coolant.

One of the major difficulties encountered in belt type casting apparatus lies in the fact that the opposite side edges of the belts must be sealed to contain the metal therein. Numerous efforts have hitherto been made to seal the side edges of the belts utilizing edge dams, either moving or stationary, or by endeavoring to bring the edges of the strip together in edge-t-o-edge contacting relationship. None of these expedients have been satisfactory in that they have introduced numerou mechanical and physical problems. For example, edge dams present problems of fabrication, alignment, cooling and maintenance. While the mechanical problems are somewhat lessened where the edges of the belts are brought together in edge-to-edge contacting relation, such ex- "ice pedient results in the production of strip material of nonuniform cross-section with appreciable areas of waste along the sides of the strip.

In contrast to the foregoing, the instant invention contemplates the use of casting belts having permanently deformed or bent side edges which, as the belts are brought together, coact to provide an integral edge closure which generates a minimum of edge scrap.

Accordingly, a principal object of the instant invention is the provision of casting apparatus wherein the casting belts are formed from spring steel the opposite side edges of which are permanently set or bent to define angularly related edge portions which, When the belts are restrained, act upon each other to effect a reverse bending of the edge portions which effectively close the opposite side edges of the casting cavity defined therebetween.

A further object of the instant invention is the provision of continuous casting apparatus of the character described incorporating forming means which engage and deflect the marginal side edges of the belts toward each other so as to initially define a casting cavity, whereupon as the belts are advanced they are contacted by sets of back-up rolls which efiect the reverse bending of the strip edges and at the same time establish the final cross-sectional dimensions of the casting cavity.

The foregoing, together with other objects of the invention which will appear hereinafter or which will be apparent to the skilled worker in the art upon reading this specification, are accomplished by that construction and arrangement of parts of which an exemplary embodiment shall now be described.

Reference is made to the accompanying drawings wherein:

FIGURE 1 is a vertical sectional view of exemplary castnig apparatus embodying the instant invention.

FIGURE 2 is a vertical sectional view illustrating a set of casting belts the edges of which are configured in accordance with the invention.

FIGURE 3 is a vertical sectional View taken along the line 3-3 of FIGURE 1 illustrating the configuration of the belts as they are contacted by the forming shoes preparatory to defining thecasting cavity.

FIGURE 4 is a vertical sectional view taken along the line 44 of FIGURE 1 illustrating the configuration of the belts after the casting cavity has been formed and the molten metal introduced therein.

FIGURE 5 is a vertical sectional view taken along the line 55 of FIGURE 1 illustrating the position assumed by the belts upon being restrained between the back-up rolls.

Referring first to FIGURE 1 of the drawings, the reference numeral 1 indicates a frame on which the apparatus is mounted, the apparatus comprising generally an upper casting belt 2 and a lower casting belt 3. At its leading end the belt 2 passes around a leading roll 4 mounted on a shaft 5 carried by opposed bearing arms 6 operatively connected to piston rod 7 forming a part of hydraulic cylinder 8. The cylinder 8 is fixedly secured to a strut 9 forming a part of the frame which mounts the upper casting belt 2. It will be understood that means will be provided for applying hydraulic pressure to the cylinder 8 so as to move the piston rod 7 and hence the roll 4 connected thereto, so as to apply tension to the belt 2. At its trailing end, the belt 2 passes around a power roll 10 rotating on a shaft 11 journaled to the supporting frame.

In somewhat similar fashion, the lower casting belt 3 is provided at its leading end with a roll 12 controlled by a hydraulic cylinder 13; and at its trailing end the lower belt 3 passes around a driving or power roll 14 which together with the power roll 10 will be driven in timed relation from a power source not shown. The driving rolls and 14 rotate in the directions indicated by the arrows A and B so as to cause the inner flight 15 of the upper belt and the inner flight 16 of the lower belt to travel in the direction of the arrow C.

As the belts 2 and 3 pass around the leading rolls 4 and 12 they are caused to converge by means of upper and lower forming shoes or flute bars 17 and 18 which, as will be explained more fully hereinafter, deflect the belts so as to define a casting cavity into which the molten metal is introduced through the refractory lined spout 19 having a mouth 20 in communication with a source of molten metal 21, which may comprise a pouring box or ladle by means of :which the molten metal may be metered to the spout.

The belts 2 and 3 will be formed from a spring steel, preferably a precipitation hardened steel such as 17-7 PH manufactured by Armco Steel Corporation. As an incident to the fabrication of the belts, and as illustrated in FIGURE 2, their opposite side edges are bent outwardly, as indicated at 22, and permanently set in the bent condition. As will be evident from FIGURE 2, the bent edges project outwardly away from the inner surfaces of the belts and are oppositely directed away from each other. The length of the bent edge portions, indicated at d, will vary depending upon the thickness of the belts, their width, and the thickness of the metal strip being cast, although generally speaking the thicker the strip being cast, the longer the length of the bent edge portions. The values for the angle x (the angle of deflection of the edge portions 22 from the plane of the strip) and the radius of curvature r will also be dependent on belt material, belt thickness, and the thickness of the strip to be cast. In an exemplary embodiment using 28 gauge steel belts, the angle x is on the order of 50 and the radius of curvature on the order of A, and a bent edge length d on the order of 2". In forming the bent edges it is to be understood that in initially bending the edges, the belts will be creased or broken through a much more severe angle-usually well in excess of 90-although due to the spring back of the metal the final angle will be 90 or less. The angle at may vary widely depending upon the nature and thickness of the material from which the belts are made, and the thickness of the strip being cast, the primary requisite being that the bent edges will be disposed at an angle such that, when restrained, the portions of the belts immediately adjacent the lines of bend will reversely bend so as to maintain sealing contact between the contacting portions of the two belts. In most installations the angle as will be on the order of from about 20 to 90 in the relaxed condition.

The leading rolls 4 and 12, as well as the trailing rolls 10 and 14, will be of cylindrical configuration, although they may be slightly crowned if desired, so that as the belts contact the rolls their bent edges tend to flatten out due to the tension on the belts. As the belts pass around the leading rolls 4 and 12 and are caused to converge by the forming shoes 17 and 18, the belts will initially assume the bowed configuration illustrated in FIGURE 3 wherein it will be seen that the bent edges of the belts are contacted by the oppositely inclined surfaces 23 and 24 of the upper and lower forming shoes 17 and 18, respectively, and it will be noted that the surfaces 23 and 24 terminate inwardly substantially conterminous with the bend lines of the belts, which lines are indicated at 25.

.The configuration of the forming shoes is such that as the belts advance their opposing marginal edges will be brought together by the time the belts reach a position in which molten metal discharged from the end of spout 19 has spread to the full width of the cast so that the opposite edges of the belts will be closed to define the casting cavity 26, as illustrated in FIG- URE 4, in which a bath of molten metal 27 is formed.

Preferably the forming shoes will be fabricated or at least surfaced with an inherently lubric material, such as Teflon or Formica, so as to reduce the friction between the belts and the forming shoes. In place of forming shoes, rolls or roll segments may be employed; but the use of such rolls requires substantially more head room than the forming shoes, which may not be available without materially increasing the size of the machine. Preferably, the forming means, whether shoes or rolls, will be positioned so as to contact the belts substantially midway between the centers of the leading belt guiding rolls 4 and 12, respectively, and the leading set of back-up rolls 28 and 29. Such positioning has been found to minimize undesirable stresses in the casting belts. In this connection, it also may be observed that the relative positions of the leading guide rolls 4 and 12 is exemplary only, the particular arrangement shown being preferred so as to readily accommodate the spout 19 and tun dish or the like supplying molten metal thereto.

When the belts are in the position illustrated in FIG- URE 4, it will be noted that their main lateral extent is of bowed configuration with the bend lines 25 in contacting relation at the innermost edges of the surfaces 23a which are configured so as to press the strips together along their bend lines, with the portions 22 projecting freely outwardly between the upper and lower forming shoes.

As the belts continue their joint movement, they pass beyond the trailing ends of the forming shoes where they are contacted by a set of back-up rolls 28 and 29 which comprise the finst in a series of back-up rolls sets acting to flatten the initially bowed strips and, as an incident of such flattening, cause the edges of the strips to reversely bend relative to each other so as to assume the condition illustrated in FIGURE 5. As seen therein, the belts have been restrained between the back-up rolls 28 and 29 with the major extent of the belts flattened to the desired final thickness of the strip being formed. The restraint imposed by the back-up rolls enforces what may be deemed a reverse bending along the opposite sides of the strips, which reverse bending acts to displace the bend lines 25 inwardly where they contact each other centrally between the spaced apart back-up TOllS with the portions of the strips lying immediately to each side of the bend lines curving outwardly at a steep angle for contact with the back-up rolls. Thus, the casting cavity becomes generally rectangular in cross-section, as indicated at 26a; and while it will be evident that there will be some Waste at each side edge of the strip being cast, such waste is minimized. At the same time, the bent edges of the belts have coacted to define integral edge dams which retain the molten metal during solidification. As the belts pass beyond the trailing set of backup rolls, indicated at 28a and 29a, the belts will be released from restraint and will return to their initially bent configuration, although they will be reflattened as they pass around the trailing rolls 10 and 14. The strip of metal, which has now solidified will be discharged from the machine onto suitable conveying rolls or the like for subsequent processing.

It will be understood that the continuous casting apparatus has been greatly simplified and parts non-essential to the instant invention omitted from the drawings. Additional details concerning belt type casting apparatus of the character employed may be found in Hazelett Patents 2,640,235 and 2,904,860, the latter disclosing a form of back-up rolls particularly suited for use with the instant invention, such rolls being provided with circumferential ridges which facilitate the cooling of the belts. Hazelett et al. Patents 3,036,348, 3,041,686, 3,123,874 and 3,142,873 are also pertinent insofar as specific details of the casting apparatus are concerned, with particular reference to the provision of means for cooling the casting belts and the provision of means for maintaining belt alignment.

Modifications may be made in the instant invention without departing from its spirit and purpose. For example, either or both sets of the forming shoes may be hydraulically controlled to adjust their relative positions. Thus, as illustrated in FIGURE 1, the upper form ing shoes 17 may be provided with hydraulic cylinders 30 by means of which the forming shoes may be adjusted. Similar cylinders may be utilized in conjunction with the lower shoes 18, although in most instances the lower shoes may be fixedly mounted so as to establish the passline of the lower belt, necessary adjustments being made by means of the upper set of shoes. It is to be understood that while the invention has been described in conjunction with apparatus wherein the casting belts are bowed at the time the casting cavity is initially formed, the bent edge principle also may be employed in apparatus wherein the main extent of the belts are planar at the time the casting cavity is formed. Other modifications will undoubtedly occur to the skilled worker in the art and it is to be understood that the invention is not to be limited in any manner other than as set forth in the claims which follow.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In apparatus for casting metal strip directly from molten metal wherein the molten metal is deposited in a casting cavity defined between flexible upper and lower traveling casting belts having coacting flights mounted one above the other for longitudinal movement in the same direction, the improvement which comprises a pair of upper and lower casting belts formed from spring steel, said belts having their opposite marginal side edges bent outwardly away from each other along permanently set lines of bend with the marginal side edges of the belts angularly disposed with respect to the portions of the belts lying between said lines of bend, the lines of bend in the upper and lower belts being in vertical alignment so as to contact each other when the belts are restrained between compressing members acting to urge the belts toward each other.

2. The casting belts claimed in claim 1 wherein said lines of bend parallel the side edges of said belts and are spaced inwardly from said side edges by a distance on the order of two inches.

3. The casting belts claimed in claim 2 wherein the edge portions of the belts lying beyond said lines of bend are at an angle of from 20 to 90 with respect to the planes of the portions of the belts lying between said lines of bend.

4. The casting belts claimed in claim 1 wherein said belts are formed from a precipitation hardened steel.

5. Apparatus for casting strips of metal directly from molten metal comprising upper and lower casting belts formed from spring steel, said belts having coacting flights mounted one above the other for longitudinal movement in the same direction and having their opposite marginal side edges bent outwardly away from each other along permanently set lines of bend, the marginal side edges of the belts being angularly disposed with respect to the portions of the belts lying between said lines of bend and the lines of bend in the upper and lower belts being in vertical alignment, forming means positioned to contact and deflect the opposite side edges of the belts inwardly causing the lines of bend in the upper belt to be juxtaposed to the lines of bend in the lower belt, and means positioned beyond said forming means for placing the belts under lateral restraint so as to restrain the portions of the belts lying between the lines of bend, such restraining means also acting to reversely bend portions of the belts immediately adjacent said lines of bend to define a generally rectangular cavity therebetween the opposite sides of which are closed by the reversely bent portions of said belts.

6. The apparatus claimed in claim 5 wherein said forming means are configured-so as to gradually bring the lines of bend at the opposite sides of the belt into eontacting relation.

7. The apparatus claimed in claim 6 wherein some at least of said forming means are adjustable toward and away from the belt contacted thereby.

8. The apparatus claimed in claim 7 wherein said forming means comprise coacting pairs of forming shoes positioned to overlie the bent edges of the belts.

9. The apparatus claimed in claim 8 wherein the belt contacting surfaces of said forming shoes are formed from a lu-bric material.

10. The apparatus claimed in claim 5 wherein the means for placing the belts under lateral restraint comprises pairs of spaced apart back-up rolls.

11. The apparatus claimed in claim 10 wherein said back-up rolls are of cylindrical configuration and are provided with spaced apart circumferential ridges.

12. The apparatus claimed in claim 5 wherein said upper and lower casting belts pass around leading guide rolls, and wherein the belts are initially contacted by said forming means substantially midway between the axes of said leading guide rolls and the points at which the belts are contacted by the means placing said belts under lateral restraint.

References Cited UNITED STATES PATENTS 6/1953 Hazelett 2257.4 9/1959 Hazelett 22-57.4 

1. IN APPARATUS FOR CASTING METAL STRIP DIRECTLY FROM MOLTEN METAL WHEREIN THE MOLTEN METAL IS DEPOSITED IN A CASTING CAVITY DEFINED BETWEEN FLEXIBLE UPPER AND LOWER TRAVELING CASTING BELTS HAVING COACTING FLIGHTS MOUNTED ONE ABOVE THE OTHER FOR LONGITUDINAL MOVEMENT IN THE SAME DIRECTION, THE IMPROVEMENT WHICH COMPRISES A PAIR OF UPPER AND LOWER CASTING BELTS FORMED FROM SPRING STEEL, SAID BELTS HAVING THEIR OPPOSITE MARGINAL SIDE EDGES BENT OUTWARDLY AWAY FROM EACH OTHER ALONG PERMANENTLY SET LINES OF BEND WITH THE MARGINAL SIDE EDGES OF THE 